Radio Shack Optimus 7 Speakers..

[kromedge]

Got through one of the speakers without any issues. The new caps are a marked difference from the old. I kept the left speaker original for comparison. Much more happening in the tweet range on the right vs. the left. Base seems to be less muddy as well. I need to get the other one capped and then on to recapping my SX780. The Opt. 7s are very impressive to say the least. I can't wait to see how they perform once my receiver is up to snuff again. Stay tuned!

 

[Steve Smiley]

Impulse purchase, thank you!

I received an email announcing 28 minutes left in an online auction...Optimus 7 speakers! I hadn’t heard of them. I had been looking for Optimus T-200 towers or Mimimus 7w to go with my Realistic 12” sub. Must be why I received the notice. Anyway, they were “pick-up only,” with no offers, 3 watching, and only 35 minutes from my house (mid-Michigan)! Is this fate? I read everything I could, with the clock winding down, and reading this entire thread, I decided to go for it. Thank you all for the inspiration. I’m pretty happy I made the purchase. The speakers have cleaned up nicely, already wife approved for our living room of antiques. Drivers are generally in good shape. Woofers are excellent with paper good and flexible. Mids a little tougher. One cone was separating from the basket. I broke away and cleaned up the brittle glue and reattached it immediately. Now mids are good to go as far as I can tell. I am wondering if there is enough travel in the cone. They seem to be moving smoothly, just not much. I should know more when I can give them a real listening.

Tweeter Twouble...

The tweeters are the unfortunate part. Only one original tweeter. The other was replaced with a driver that seems to be found in a few of the RS Nova variants. Seems more like a good mid than a good tweeter. When I connected them to the test bench they seemed to be reproducing a significant portion of the entire frequency range. I was really hoping for all-original. Does anybody know how I can get one. I haven’t been able to find any online. Some alnico magnet alternatives may be some Pioneer or Kenwood drivers but haven’t found a fit yet. Does any kind soul out there have an original spare tweeter you would be willing to part with? I’m not sure if a damaged one could be repaired but I do have a speaker repair shop about an hour away that does excellent work. I learned of their shop through a recommendation from Ken Kreisel, of M & K fame (great guy, by the way, and how I got interested into vintage...)

I have ordered all the replacement caps and look forward to getting started. Also ordered the donut magnets from China that some have mentioned. Let the adventure begin! I’m excited for any advice or support the community can offer. I’m happy to share my findings as well. I owe it all to you (the impulse purchase!) and I think I’m going to love the final product!

Regards and happy tinkering/listening!

 

[woofercooker]

Welcome Steve! I saw those speakers on the the bay and thinking someone should buy them at that price even with the wrong tweeter. If you can't find an exact replacement tweeter, I would use a Criterion CR tweeter (pair). They are an exact fit. They do sound a little quieter than the originals but sound decent. Thats why I would use them in pairs. I'm using a pair of them in one of my pairs of Opt 7. They are pretty cheap, too. You can always turn up the tweeter control to get the more treble. What caps did you get? Keep us posted.....

 

[Steve Smiley]

Thank you for the welcome woofercooker! I'm really having fun with this. I'm using Dayton Audio polypro caps, as Ukfan4sure! posted. I've made it halfway through the first recap. Those polypro caps get big. Some real creative work to fit 22 uf in the general vicinity of the original electrolytics, but so far so good. I think I have the toughest two done.I expect I'll make more progress on the recap job this weekend. I ordered a couple tweeters from Parts Express to try out when I ordered my new caps. I got a pair of the phenolic ring copies that have been mentioned in this thread.I'll give those a listen but I don't really want to enlarge the tweeter cut outs, in hopes that I can find a replacement original. I also grabbed the mini AMT tweeter at 8 Ohm to give that a go, with no real idea if it will work or not. When you mention Criterion CR, I find the Criterion CR-100B, but not really sure if that is what you mean. I like the idea of replacing it with another alnico magnet number. That is why I mentioned that I saw a few Pioneer and Kenwood variants that I thought might fit the bill. Bottom line, I haven't done any serious listening to any of the alternative tweeters. I've learned more that I believe the non-original tweeter that came with this pair is from a Nove 5B - an 0725Ac - that is supposed to be a respectable speaker in it's own right, so maybe half the answer I already have...

Thinks got worse on the midrange that I thought I repaired. The paper started to tear at the surround. I used some seam sealer from Simply Speakers to fix it. It sealed it up good but now I've really stiffened up the surround. I haven't done a listening test but if it's a bust I may be looking for an alternative for the mid as well. I won't give up so easily on the mid yet. I think I could put new surrounds on it if necessary and be good to go!

So a few questions pop in my head... as was mentioned here, do I want to add some mass to the baffle on the mid? I have some sound deadener sheets for car doors from Parts Express that might do a nice job, versus the electrical tape that was suggested. It's just sitting in the box, so no harm in trying. Also, anybody try to stuff the heck out of the cabinet with acousta-stuff? I see one of our contributors preferred adding a bit more to the bottom of the cab. I'll kick that around. I love the fact that there are threaded inserts to mount the drivers. Makes it a hole lot better for trying lots of different stuff out.

Here's the real neat part. I plugged in just one all-original speaker (old caps) and listened to it while I was working on this project. Damn, if it didn't sound promising...! I'm excited for the end results.

I've been so wordy, thank you for entertaining my rambling. I get this way when I'm excited...

 

[quiet]

Hi Steve. Yes I tried stuffing one with fiberglass a few years ago. It didn't work. It made a small improvement in bass extension with a very early and steep roll off. Not good. So I then went in the other direction.
I lined all the walls with cotton batting. This brought a large reduction in roll off which presented as improved bass sensitivity. And no bass bump any where.
So, more good usable bass before roll off. It sounded a lot better.
I've had similar results with other sealed speakers. I think the batting cost more than the stuffing or it would have been used more.

 

[Steve Smiley]

Thank you Quiet, I appreciate the feedback. I had just picked up a huge box of poly-fil, as well as some memory foam egg crate padding. I also started on building some stands last night. I bet you just saved me a bunch of time! Let see where I can find some cotton batting on the cheap. I'll post my results of my experiments. I'm very please with the high and mid frequencies (a special thank you to Woofercooker!) and now the bass needs some presence. I have to believe placement is a big part of this as well. My location doesn't seem ideal, and yet I don't have tons of options...

 

[quiet]

The batting I used came from several used sofas. I hear new batting is hard to find.
If you try the poly you will have a feel for what's going on and needed. Sometimes it helps to know what doesn't work first hand. So you don't wonder what if.
The stuffing method showed promise but needed a "lot" of bass boost from the EQ. I didn't think the woofer coil could take the watts needed to keep up with the new roll off.
Sometimes one change allows another to work. In my case the batting cleaned up the bass enough that they could be used and worked best on the floor. But on the floor and in the corner was to much.
If the batting had not worked by itself my next move would have been several 1/2 inch vertical slots on the rear panel, probably 12 inches long, also with the batting.
I came to the conclusion the box is good and they would benefit from a better woofer. I didn't pursue it any farther and sold mine because used parts looked hard to find if needed.
Welcome to AK and good luck.

 

[Steve Smiley]

Thank you Quiet, you've helped me embrace that I need to really be patient and enjoy the problem solving aspect of this. I've learned so much through my following in AK, I need to start trusting what I'm learning. I'll keep my eyes open for old couches, etc. I live next to a college town, so there is usually no shortage of furniture on the curb! I guess I shouldn't be surprised that I'm not getting the bass I want out of these. I'm certain they are capable of more. I had a thought last night that I might also want to consider my source. I was using an old ipod in a dock. When I upped the bass on the built in EQ on the iPod I heard some improvement. We'll get there...

 

[premiumplus]

Hey Steve, I'm in Mid-Michigan too. I've had 4 Optimus 7 speakers since 1973. I used to manage a Radio Shack out in So. Calif. and we were surprised and disappointed when they discontinued these great speakers. They sound better today than many very expensive speakers do. I blew and replaced my tweeters the first year I had those speakers...and I just got a good sounding horn tweeter and replaced them. They sound great; I think you could use any quality tweeter that will fit. The crossovers are great.
Enjoy your speakers. You got gold there, buddy!

 

[ukfan4sure!]

I'm just now getting back to this thread after a long hiatus from AK. I just bought a MAC 1900 and will be re-capping it soon. I got to looking at old posts and found I've missed the boat on a lot of conversation on my old Optimus 7's. Still tried and true, the only speakers that have been in the stable that have found a home along with these are some Dynaco a25's (best low-volume performer I've ever heard), and some TL's I built from a kit from Parts Express.

I am so please to see so many fans of these speakers!!

 

[paysonmark]

welcome back, Im been enjoying my recapped OPTI '7s with tube amps, sounds sooo much better.
Could you do me a favor and measure the ohms at the input jack. Just want to compare with mine....
thx
have a great day

 

[Kevinly]

[QUOTE="

 

[Kevinly]

I have spare crossovers with broken shaft on LPAD know of a good replacement part or how to fix.Jst recently found 7s blend well with Blend well with ALTEC Valencias

 

[Kevinly]

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Plan on crossover work on spares before pulling out old ones

 

[caltechi]

Now don't hate on me but I just picked up a set of these offered for free on CL. I had seen Optimus 7s before but it has been a while so I did't recognize them from the photo in the add. They were advertised as big mid-century speakers from the 70s. The add said that they worked but I wasn't really all that concerned as they were free. My thought was that maybe I would find some JBL or Altec drivers I could harvest from the cabinet for a DIY project down the road. (like I need another project) When I picked them up, the owner said that her dad bought them new in 73 or 74 and left them to her in his will. They were being used in the bedroom as nightstands/TV speakers and the owners said the they always thought the speakers sounded really good. The TV got moved and new nightstands were bought so these beauties came home with me.

All in all they're in decent shape but need some love. A good cleaning of the cabinets and drivers are in order as well as the typical cleaning of scratchy L-pads and a recap. The upshot is that all the drivers are working and aside from being rather dusty are in terrific shape. So needless to say that after reading the threads regarding these speakers my plans to harvest them has changed to restoration. I hooked them up to my SX-636 that I recently restored and was pleasantly surprised with the sonic quality. I concur with what others have said with regard to imaging, clarity and bass response. This was especially apparent when I listened to the acoustic version of "Undone" by Duran Duran. I did have to get the volume to about 3 o'clock with my little 40 watt SX-636 (I upgraded the output devices) to really hear them sing but there was no detectable distortion; even at full volume.

I'm very pleased with these speakers and am looking forward to the restoration journey that lies before me. I will definitely be drawing on all the tribal knowledge in this thread from those who have gone before me and I'll keep you all posted. Pics below:

In the shop accompanied by some AR 4x's. Nothing goes better with vintage speakers than vintage speakers!


A couple of "nudies"


Pioneer SX-636 sitting proudly atop the beasties

 

[Steve Smiley]

No hate, but perhaps a little envy! Great find and enjoy bringing them back up to snuff. They look quite good already! My Optimus 7 passed the WAF and are in our living room. Really lookin’ good! Enjoy!

I am going to apply some treatment on my woofer surrounds to see if they will improve my bass. This stuff is from Larry of Vintage-AR on the Bay and is supposed to seal and renew flex to the dry cloth surrounds. As soon as it warms up another ten degrees or so, maybe this weekend, I’ll give it a whirl. I’ll report back my findings.

Congrats again, Caltechi, enjoy!

 

[caltechi]

Thanks Steve!

Yeah definitely let us all know how goes the cloth surround renewal.

 

[fredgarvin]

Very nice, there was a set for sale here for $300, with nicked up cabinets, but he chose to list them at Christmas, so I and everyone else was broke. He then teamed them up with a bunch of radio Shack equipment and that sold apparently.

 

[Pointed]

Truly need some treatment on dry cloth woofer surrounds for Optimus 7, here are what I have done (by cheap way),
Apply thin vaseline on front side cloth surrounds, let it stay for 24h then burn-in few hours at 50hz, finally clean the surface of cloth surrounds by tissue paper. The motions of woofer cone very much improved.

For your information.

 

[Pointed]

Trying my new “toy”, looking not vintage as previous bullet tweeters.

Is there anyone experience this kind of tweeter before? Please be advised